 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.views.framelist;

 import java.util.ArrayList ;
 import java.util.List ;

 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.jface.viewers.AbstractTreeViewer;
 import org.eclipse.jface.viewers.ILabelProvider;
 import org.eclipse.jface.viewers.ISelection;
 import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.jface.viewers.StructuredSelection;
 import org.eclipse.ui.IElementFactory;
 import org.eclipse.ui.IMemento;
 import org.eclipse.ui.IPersistableElement;
 import org.eclipse.ui.PlatformUI;

 /**
  * Frame for tree viewers. This capture the viewer's input element, selection,
  * and expanded elements.
  */
 public class TreeFrame extends Frame {
     private static final String TAG_SELECTION = "selection"; //$NON-NLS-1$

     private static final String TAG_EXPANDED = "expanded"; //$NON-NLS-1$

     private static final String TAG_ELEMENT = "element"; //$NON-NLS-1$

     private static final String TAG_FRAME_INPUT = "frameInput"; //$NON-NLS-1$

     private static final String TAG_FACTORY_ID = "factoryID"; //$NON-NLS-1$

     private AbstractTreeViewer viewer;

     private Object input;

     private ISelection selection;

     private Object [] expandedElements;

     /**
      * Constructs a frame for the specified tree viewer.
      * The frame's input, name and tool tip text are not set.
      *
      * @param viewer the tree viewer
      */
     public TreeFrame(AbstractTreeViewer viewer) {
         this.viewer = viewer;
     }

     /**
      * Constructs a frame for the specified tree viewer.
      * The frame's input element is set to the specified input element.
      * The frame's name and tool tip text are set to the text for the input
      * element, as provided by the viewer's label provider.
      *
      * @param viewer the tree viewer
      * @param input the input element
      */
     public TreeFrame(AbstractTreeViewer viewer, Object input) {
         this(viewer);
         setInput(input);
         ILabelProvider provider = (ILabelProvider) viewer.getLabelProvider();
         String name = provider.getText(input);
         if(name == null) {
             name = "";//$NON-NLS-1$
 }
         setName(name);
         setToolTipText(name);
     }

     /**
      * Returns the expanded elements.
      *
      * @return the expanded elements
      */
     public Object [] getExpandedElements() {
         return expandedElements;
     }

     /**
      * Returns the input element.
      *
      * @return the input element
      */
     public Object getInput() {
         return input;
     }

     /**
      * Returns the selection.
      *
      * @return the selection
      */
     public ISelection getSelection() {
         return selection;
     }

     /**
      * Returns the tree viewer.
      *
      * @return the tree viewer
      */
     public AbstractTreeViewer getViewer() {
         return viewer;
     }

     /**
      * Restore IPersistableElements from the specified memento.
      *
      * @param memento memento to restore elements from
      * @return list of restored elements. May be empty.
      */
     private List restoreElements(IMemento memento) {
         IMemento[] elementMem = memento.getChildren(TAG_ELEMENT);
         List elements = new ArrayList (elementMem.length);

         for (int i = 0; i < elementMem.length; i++) {
             String factoryID = elementMem[i].getString(TAG_FACTORY_ID);
             if (factoryID != null) {
                 IElementFactory factory = PlatformUI.getWorkbench()
                         .getElementFactory(factoryID);
                 if (factory != null) {
                     elements.add(factory.createElement(elementMem[i]));
                 }
             }
         }
         return elements;
     }

     /**
      * Restore the frame from the specified memento.
      *
      * @param memento memento to restore frame from
      */
     public void restoreState(IMemento memento) {
         IMemento childMem = memento.getChild(TAG_FRAME_INPUT);

         if (childMem == null) {
             return;
         }

         String factoryID = childMem.getString(TAG_FACTORY_ID);
         IAdaptable frameInput = null;
         if (factoryID != null) {
             IElementFactory factory = PlatformUI.getWorkbench()
                     .getElementFactory(factoryID);
             if (factory != null) {
                 frameInput = factory.createElement(childMem);
             }
         }
         if (frameInput != null) {
             input = frameInput;
         }
         IMemento expandedMem = memento.getChild(TAG_EXPANDED);
         if (expandedMem != null) {
             List elements = restoreElements(expandedMem);
             expandedElements = elements.toArray(new Object [elements.size()]);
         } else {
             expandedElements = new Object [0];
         }
         IMemento selectionMem = memento.getChild(TAG_SELECTION);
         if (selectionMem != null) {
             List elements = restoreElements(selectionMem);
             selection = new StructuredSelection(elements);
         } else {
             selection = StructuredSelection.EMPTY;
         }
     }

     /**
      * Save the specified elements to the given memento.
      * The elements have to be adaptable to IPersistableElement.
      *
      * @param elements elements to persist
      * @param memento memento to persist elements in
      */
     private void saveElements(Object [] elements, IMemento memento) {
         for (int i = 0; i < elements.length; i++) {
             if (elements[i] instanceof IAdaptable) {
                 IPersistableElement persistable = (IPersistableElement) ((IAdaptable) elements[i])
                         .getAdapter(IPersistableElement.class);
                 if (persistable != null) {
                     IMemento elementMem = memento.createChild(TAG_ELEMENT);
                     elementMem.putString(TAG_FACTORY_ID, persistable
                             .getFactoryId());
                     persistable.saveState(elementMem);
                 }
             }
         }
     }

     /**
      * Save the frame state in the given memento.
      *
      * @param memento memento to persist the frame state in.
      */
     public void saveState(IMemento memento) {
         if (!(input instanceof IAdaptable)) {
             return;
         }

         IPersistableElement persistable = (IPersistableElement) ((IAdaptable) input)
                 .getAdapter(IPersistableElement.class);
         if (persistable != null) {
             IMemento frameMemento = memento.createChild(TAG_FRAME_INPUT);

             frameMemento.putString(TAG_FACTORY_ID, persistable.getFactoryId());
             persistable.saveState(frameMemento);

             if (expandedElements.length > 0) {
                 IMemento expandedMem = memento.createChild(TAG_EXPANDED);
                 saveElements(expandedElements, expandedMem);
             }
             // always IStructuredSelection since we only deal with tree viewers
 if (selection instanceof IStructuredSelection) {
                 Object [] elements = ((IStructuredSelection) selection)
                         .toArray();
                 if (elements.length > 0) {
                     IMemento selectionMem = memento.createChild(TAG_SELECTION);
                     saveElements(elements, selectionMem);
                 }
             }
         }
     }

     /**
      * Sets the input element.
      *
      * @param input the input element
      */
     public void setInput(Object input) {
         this.input = input;
     }

     /**
      * Sets the expanded elements.
      *
      * @param expandedElements the expanded elements
      */
     public void setExpandedElements(Object [] expandedElements) {
         this.expandedElements = expandedElements;
     }

     /**
      * Sets the selection.
      *
      * @param selection the selection
      */
     public void setSelection(ISelection selection) {
         this.selection = selection;
     }
 }

